Fundamental equations of hydrodynamics
From AMS Glossary
fundamental equations of hydrodynamics
The equations of motion, the equation of continuity, the energy equation, the equation of state, and the equation of continuity for water substance, considered together as a closed system of equations.
A simplified physical model can dispense with certain of these equations without sacrificing completeness; for example, in two-dimensional homogeneous incompressible flow, kinetic energy is the only form of energy, and the equations of motion and continuity form a closed system.